# computing forward solutions separately for MEG and EEG **URL:** \ **Category:** Mailing List Archive (read-only)\ **Tags:** list-archive\ **Created:** [January 7, 2015, 2:22pm UTC](https://mne.discourse.group/t/computing-forward-solutions-separately-for-meg-and-eeg/895 "2015-01-07T14:22:28Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\ **Post date:** [January 7, 2015, 2:22pm UTC](https://mne.discourse.group/t/computing-forward-solutions-separately-for-meg-and-eeg/895/1 "2015-01-07T14:22:28Z")
Dear mne users, at first and before all: Happy New Year to the list! Then, back to work 😉 : I recently tried to compute separate forward models for MEG, EEG and combined EEG/MEG with the mne suite and mne\_do\_forward\_solution here is the bash code I used for the MEG-only computations: arr1=($ListSubj) > Dir=/neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/MEG/ > > for i in {0..19}; do >     echo ${arr1[i]} > > export SUBJECTS\_DIR=/neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/mri/ > export SUBJECT=\{arr1\[i\]\} export MEG\_DIR=/neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/MEG/{arr1[i]}/mne\_python > > # for MEG > mne\_setup\_source\_space --ico 5 -overwrite > mne\_setup\_forward\_model --homog --surf --ico 4 > > mne\_do\_forward\_solution --mindist 5 --spacing ico-5 --mricoord > Dir{arr1[i]}/raw\_sss/run3\_DG\_trans\_sss-trans.fif --meas > Dir{arr1[i]}/raw\_sss/run3\_DG\_trans\_sss.fif --bem ${arr1[i]}-5120.fif > --megonly --overwrite --fwd $MEG\_DIR/run3\_ico-5\_megonly\_-fwd.fif > > done and it worked fine. For EEG only, I modified the code to use a 3 layer BEM (remove --homog option in mne\_setup\_forward\_model) and use the --eegonly option in mne-do-forward solution. arr1=($ListSubj) > Dir=/neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/MEG/ > > for i in {0..1}; do >     echo ${arr1[i]} > > export SUBJECTS\_DIR=/neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/mri/ > export SUBJECT=\{arr1\[i\]\} export MEG\_DIR=/neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/MEG/{arr1[i]}/mne\_python > > # for EEG > > mne\_setup\_source\_space --ico 5 -overwrite > mne\_setup\_forward\_model --surf --ico 4 > > mne\_do\_forward\_solution --mindist 5 --spacing ico-5 --mricoord > Dir{arr1[i]}/raw\_sss/run3\_DG\_trans\_sss-trans.fif --meas > Dir{arr1[i]}/raw\_sss/run3\_DG\_trans\_sss.fif --bem ${arr1[i]}-5120.fif > --eegonly --overwrite --fwd $MEG\_DIR/run3\_ico-5\_eegonly\_-fwd.fif > > done Then I got this error: Read 306 MEG channels from > /neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/MEG/cb130477/raw\_sss/run3\_DG\_trans\_sss.fif > Read 61 EEG channels from > /neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/MEG/cb130477/raw\_sss/run3\_DG\_trans\_sss.fif > MEG not requested. MEG channels omitted. > Some EEG channels do not have locations assigned. > Forward computation failed (see above) As I understood, if EEG channel number \>60, it could raise an error and prevent mne to retrieve channel location. So I tried the dedicated fix: mne\_check\_eeg\_locations mne\_check\_eeg\_locations --file > Dir{arr1[i]}/raw\_sss/run3\_DG\_trans\_sss-trans.fif --fix and got: mne\_check\_eeg\_locations version 1.2 compiled at Jan 5 2015 04:22:49 > input file : > /neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/MEG/sd130343/raw\_sss/run3\_DG\_trans\_sss-trans.fif > digitizer data file : > /neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/MEG/wl130316/raw\_sss/run3\_DG.fif > > Checking... > Could not find the channel information. I suspect that the EEG064 reference is the problem so I try to modify directly the EEG status of this channel with mne\_rename\_channels and the following alias: "EEG064:MISC666:502" in a text file, trying to transform this problematic channel into a harmless MISC. mne\_rename\_channels --fif > Dir{arr1[i]}/raw\_sss/run3\_DG\_trans\_sss-trans.fif --alias > /neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/SCRIPTS/define\_aliases.txt and got: mne\_rename\_channels version 1.5 compiled at Jan 5 2015 04:17:51 > fif file : > /neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/MEG/sd130343/raw\_sss/run3\_DG\_trans\_sss-trans.fif > alias file : > /neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/SCRIPTS/define\_aliases.txt > 1 aliases read from > /neurospin/meg/meg\_tmp/MTT\_MEG\_Baptiste/SCRIPTS/define\_aliases.txt > 0 changes done So it appears that it didn't change anything. I checked that this EEG064 is in the fiff file and I confirmed it exists from fiedtrip header content of the same file. I'm a bit stuck at this step and would appreciate any feedback on my unlucky attempts :). Best regards, Baptiste ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\ **Post date:** [January 7, 2015, 5:13pm UTC](https://mne.discourse.group/t/computing-forward-solutions-separately-for-meg-and-eeg/895/2 "2015-01-07T17:13:52Z")
hi Baptiste, it seems you did the right things in the right order. are you sure the channel is called "EEG064" in the fif file? no space? "EEG 064"? otherwise to debug this please share the file or fire up a python shell and inspect info obtained with info = mne.io.read\_info('fname\_raw.fif') HTH Alex